Automobile ignition security systems may utilize a Hall-effect magnetic sensor which contains a single Hall-effect element located in the ignition switch lock assembly to generate a specific voltage code. This code is utilized by a microprocessor of the ignition system of the vehicle to start the automobile. The Hall-effect sensor is located in the lock sleeve and is activated by a magnet located in the lock cylinder. The magnet in the lock cylinder provides a magnetic flux that is necessary to turn on the Hall-effect sensor. During normal operation, the magnet is rotated past the Hall-effect sensor and the output voltage of the Hall-effect sensor changes from a high level to a low level resulting in a set voltage at the output of the Hall-effect sensor. The output is latched and remains low when the magnet is rotated past the Hall-effect sensor, and the magnetic flux density decreases to a level below that which is necessary to turn on the Hall-effect sensor.
Ignition security systems may further include an additional Hall-effect sensor, that contains a single Hall-effect element which is used to detect an external magnetic field. This additional Hall-effect element is utilized as an anti-theft mechanism to deter unauthorized use of automobiles. The additional Hall-effect sensor turns on before the main Hall-effect sensor turns on thereby sending an improper voltage code to the microprocessor of the ignition system of the vehicle to prevent the vehicle from starting. The use of two Hall-effect sensors provides for an ignition security system; however, there remains a need for an improved ignition security system that provides a reliable, low cost anti-theft and/or tampering mechanism for automobile ignition security systems.